Picomolar concentrations of oligomeric alpha-synuclein sensitizes TLR4 to play an initiating role in Parkinson's disease pathogenesis.

Change log
Hughes, Craig D 
Choi, Minee L 
Ryten, Mina 
Hopkins, Lee 
Drews, Anna 

Despite the wealth of genomic and transcriptomic data in Parkinson's disease (PD), the initial molecular events are unknown. Using LD score regression analysis, we show significant enrichment in PD heritability within regulatory sites for LPS-activated monocytes and that TLR4 expression is highest within human substantia nigra, the most affected brain region, suggesting a role for TLR4 inflammatory responses. We then performed extended incubation of cells with physiological concentrations of small alpha-synuclein oligomers observing the development of a TLR4-dependent sensitized inflammatory response with time, including TNF-α production. ROS and cell death in primary neuronal cultures were significantly reduced by TLR4 antagonists revealing that an indirect inflammatory mechanism involving cytokines produced by glial cells makes a major contribution to neuronal death. Prolonged exposure to low levels of alpha-synuclein oligomers sensitizes TLR4 responsiveness in astrocytes and microglial, explaining how they become pro-inflammatory, and may be an early causative event in PD.

Aggregation, Alpha-synuclein, Innate immunity, Parkinson’s disease, TLR4, Animals, Astrocytes, Brain, Cell Death, Cytokines, Humans, Inflammation, Microglia, Neurons, Parkinson Disease, Substantia Nigra, Toll-Like Receptor 4, alpha-Synuclein
Journal Title
Acta Neuropathol
Conference Name
Journal ISSN
Volume Title
Springer Science and Business Media LLC
European Research Council (669237)
This work was supported by ARUK. AD was financed by a Herchel Smith Postdoctor-al Fellowship. DK acknowledges funding from the Royal Society and ERC Advanced Grant (669237). SG and ML acknowledge funding by Wellcome.